Cobalt/zinc oxide hollow spheres: Visible light nanophotocatalysts

Organic dyes used by food and textile industries, e.g. Malachite green dye (MG), contaminate surface and ground waters. Photocatalysis with ultraviolet light (UV) irradiation of zinc oxide (ZnO) nanoparticles can remove such industrial effluents. However, to more efficiently use solar energy, a photocatalyst active over a wider range of the visible light spectrum remains desirable for environmental remediation. Thus, we synthesized visible light photoactive cobalt/zinc oxide hollow sphere nanostructures with a hydrothermal process, and we used a number of characterization techniques to confirm that doped cobalt (Co) ions replace some zinc (Zn) ions in the lattice. The as-prepared Co doped hollow spheres performed 55.9 times better in Malachite green dye visible light photodegradation tests than similar ZnO nanoparticles. Furthermore, the Co/ZnO hollow spheres are recyclable.